This movie is almost amazing and funny and touching, but somehow, it just misses the mark. The fault really isn't the actors, they are superb (Toni Collette is great in everything she does.) And the fault certainly isn't the ABBA-centered soundtrack playing in the background; it adds some much-needed levity to a very heavy comedy-drama.
The first major problem of the movie is that it can't decide whose story it is. You would think with a title like Muriel's Wedding that we would see things through Muriel's point of view. But so many times, we're taken off on these scenes without Muriel, where we catch a glimpse of Rhonda's thoughts or the mother's feelings. It gives a disjointed feel to the movie, keeping us from focusing on Muriel, the supposed object of our admiration and encouragement.
The movie also offers drama to the point of the extreme, and it can't really recover from the depressing story lines that pop up periodically. Very few directors and screenwriters know how to make a drama light-hearted and amusing. Billy Wilder was one. If he had directed Muriel's Wedding, it really would have been something to stand up and cheer about. This movie has a character with a cancerous tumor who will never walk again, a woman who feels so worthless she commits suicide, a father who is cheating on his wife and verbally abusing his children, and Muriel, who is obsessed with weddings and ABBA, a trait which might be funnier if there weren't all this other mess going on. Ultimately, we like Muriel, but we'd like her more if we saw more of her, and less of her dysfunctional friends and family.